Friction particle for brake lining

ABSTRACT

A friction particle, useful in applications where cashew nut shell oil friction particles have been used, may be prepared by the reaction at a temperature from about 225 to about 400 degrees Fahrenheit of a non-oxyalkylated resole with resin selected from the group consisting of an oxyalkylated resole, an alkylated resole, an alkylated novolac, an oxyalkylated novolac, and mixtures thereof until it is insoluble, infusible, and does not soften slightly under mechanical force at temperatures below about 400 degrees Fahrenheit, and has substantially no cohesive or bonding strength.

m 1 nite States Patent [191 [111 3,852,811 t Grazen et al. 1| c. 31, 11974 [54] FRICTION PARTICLE FOR BRAKE LINING 2,894,931 7/1959 Somerville et al. 260/838 ,7,96 2961D' tl. ..26 3 [751 lnvenmrs: Frank Melvin Bllke; ,i7i,0 0 4ii965 as ef ei af 268/332 Frank Bryzmsky, all Of North 3,455,868 7/1969 D'Alessandro 260/838 Tonawan a, NY. 3,658,751 4/1972 Grazen et al. 260/838 [73] Assignee: Hooker Chemical Corporation,

Ni F ll N Y Primary Examinerl.:l ohn BleultgeC J F Filed: Dec 27,1972 fizz/grey, Agent, or zrm eter ase a, ames [21] Appl. No.: 318,795

Related US. Application Data [57] ABSTRACT Division Of 98, Oct. 1971, A friction particle, useful in applications where cawhCh a dlvlslon of 872,753 shew nut shell oil friction particles have been used, 1969 may be prepared by the reaction at a temperature from about 225 to about 400 degrees Fahrenheit of a [52] Cl 260/38 260/19 260/19 non-oxyalkylated resole with resin selected from the 260/39 260/39 260/515 260/838 group consisting of an oxyalkylated resole, an alkyl- 260/840 ated resole, an alkylated novolac, an oxyalkylated no- [51] m Cl Cosg 37/18 C0 g 5 volac, and mixtures thereof until it is insoluble, infus- Fleld of Search 38, b and does not soften under mechanical force at temperatures below about 400 degrees Fahr- [56] References Cited enheit, and has substantially no cohesive or bonding lJNITED STATES PATENTS strength 2,625,530 1/1953 Doelling et al. 260/838 2,626,942 1/1953 De Groote 260/838 9 Clam, N0 Drawmgs 1 FRICTION PARTICLE FOR BRAKE LllNlNC This is a division of co-pending application SN 188,598, filed Oct. 12, 1971, now US. Pat. No. 3,781,241, issued Dec. 25, 1973; which is a division of application Ser. No. 872,753, filed Oct. 30, 1969, now U.S. Pat. No. 3,658,751.

This invention relates to novel cured phenolic resins to be used as a friction particle material. It is especially useful where cashew nut shell oil friction particles, called Cardolite, have been used in the past.

Phenol aldehyde, or hydroxy aromatic-aldehyde condensation products having methylol side or end groups are known in the art as resoles. They are formed from condensing a phenol with an excess of aldehyde and an alkaline catalyst, also known as one-stage" resins and are of the thermosetting type. Except when oxyalkylated, they are self-setting. That is, upon the application of heat there results the formation of a resite, which is an infusible three-dimensional polymer.

Novolac phenol aldehyde resins, on the other hand, are phenol ended chain polymers. They are formed by the reaction of an aldehyde with an excess of phenol in the presence of an acid catalyst and/or heat. They are thermoplastic, permanently soluble and fusible. However, upon the addition of a curing agent, they can be cured into an insoluble, infusible resin. Thus, novolac resins are known as two-stage resins.

Phenol aldehyde condensation products have been used as binders for abrasive materials. However, to our knowledge, the novel cured phenol aldehyde products of this invention have not been used as a friction particle per se.

As used herein friction particle is intended to mean having the properties of substantially no softening at elevated temperaturs and will not flow together or cohere with other particles, as a friction binder would, or fuse with like friction particles, It is insoluble, having an acetone extraction of less than 35 percent and often less than 5 percent; it is infusible, i.e., has gone beyond the B stage, to the C stage. It will not melt at 700 degrees Fahrenheit A friction particle is .held in place with a friction binder.

As used herein, a friction binder has the properties of flowability, and has adhesive and cohesive bonding action and thereby binds together the asbestos and other additives (including a friction particle) necessary for building a brake lining or other similar article of manufacture. The binder, as supplied to the industry, will melt as a dry opowder or is a liquid resin, and can be either an A stage or B stage resin. The binder becomes a C stage resin after it is combined with the other ingredients and cured.

This composition of the binder, friction particle and other additives, is heated to about 300-400 degrees F. and pressed at about 500-2000 pounds per square inch in order to form a brake lining composition, or clutch facing or other braking device. Thus, the friction particle is substantially insoluble and infusible, softening only at elevated temperature (i.e., above about 400-500 degrees F.).

It has now been found that a composition of matter useful as a friction particle can be prepared by the reaction at a temperature from about 225 to about 400 degrees Fahrenheit of a non-oxyalkylated hydroxy aromatic hydrocarbon-aldehyde resole with a resin selected from the group consisting of an oxyalkylated hydroxy aromatic hydrocarbon-aldehyde resole, an alkylated hydroxy aromatic hydrocarbon-aldehyde resole, an alkylated hydroxy aromatic hydrocarbon-aldehyde novolac, an oxyalkylated hydroxy aromatic hydrocarbon-aldehyde novolac, and mixtures thereof, until it is insoluble, infusible, and does not soften slightly under mechanical force, such as a spatula, at temperatures below about 400 degrees F., and has substantially no cohesive or bonding action or strength. The crude material is initially in lump form, which is then ground to the size specification of the customer. The first sold rcsole can be alkylated but not oxyalkylated. Among the preferred embodiments ofthis invention are the followmg:

l. The reaction product of between about 5 and about 40 percent by weight of an oxyalkylated resole with between about 95 and about 60 percent by weight of one or more of a. one or more non-oxyalkylated, non-alkylated resoles,

b. a non-oxyalkylated, alkylated resole,

c. a mixture of a non-oxyalkylated alkylated resole and a non-oxyalkylated, non-alkylated resole,

d. a mixture of a non-oxyalkylated, non-alkylated resole and a non-oxyalkylated alkylated novolac, and

e. a mixture of a non-oxyalkylated, non-alkylated novolac and a non-oxyalkylated, non-alkylated resole.

2. The reaction product of between about 95 and about 60 percent by weight of a non-oxyalkylated, nonalkylated resole with between about 5 and about 40 percent by weight of one or more of a. an oxyalkylated novolac, and

b. a non-oxyalkylated, alkylated resole.

3. The reaction product of between about 5 and about 40 percent by weight of an oxyalkylated novolac with between about 95 and about 60 percent by weight of one or more of a. two or more non-oxyalkylated, non-alkylated resoles,

b. an alkylated resole,

c. a mixture of an alkylated resole and a nonoxyalkylated, non-alkylated resole,

d. a mixture of a non-oxyalkylated, non-alkylated resole and a non-oxyalkylated alkylated novolac, and

e. a mixture of a non-oxyalkylated, non-alkylated resole and a non-oxyalkylated, non-alkylated novolac.

4. The reaction product of between about 5 and about 95 percent by weight of a solid, B-stage nonoxyalkylated, alkylated resole, with between about 95 and about 5 percent by weight ofa liquid, A-stage, nonoxyalkylated, alkylated resole.

5. The reaction product of between about and about percent by weight of a non-oxyalkylated, alkylated resole, with between about 30 and about 10 percent by weight of a non-oxyalkylated, alkylated novolac.

6. The reaction product of between about 5 and about 50 percent by weight of a non-oxyalkylated, alkylated resole, with between about 5 and about 30 percent by weight of a non-oxyalkylated, alkylated novolac, and with between about 25 and about 90 percent by weight of a non-oxyalkylated, non-alkylated resole.

In general, an oxyalkylated hydroxy aromatic material, whether it is a novolac or a resole, will not react with a novolac by itself. The methylol groups on a resole are believed to be needed to react with the polyol groups of the oxyalkylated materials.

The friction particle is formed by blending and reacting the resole with the novolac, or oxyalkylated resole. Usually, the resole and oxyalkylated resole or oxyalkylated novolac are both liquids, so blending is easily achieved. However, when one is a solid, it is powdered and mixed with the liquid. When both are solids, both are dry blended such as by ball milling together. Then they are mechanically blended, such as by being passed through a hammer mill equipped with a quarter mesh screen.

Following blending, the resins are heated to about 225 degrees F. to about 400 degrees F., and preferably from about 325 degrees F. to about 375 degrees F., until a resin of friction particle consistency is formed.

Examples of phenols which can be used in preparing a phenol aldehyde resole or novolac for use in practicing the invention include ortho-, paradirecting hydroxy or amino aromatic compounds having 6 to 24 carbon atoms such as phenol itself (C l-l Ol-l), naphthol, anthranol and substituted derivatives thereof where the substituents on the aromatic compound are independently selected from M, Cl, Br, F, Nl-l and a. alkyl groups or radicals of l to 60 carbon atoms, preferably of l to 30 carbon atoms, and their various isomeric forms and substituted on the aromatic nucleus in the ortho or para position;

b. cycloalkyl groups of 5 to 12 carbon atoms such as cyclohexyl, cyclopentyl, methylcyclohexyl, butylcyclohexyl, and so forth;

c. alkyl, aryl and cycloalkyl ketonic groups wherein the hydrocarbon portion is as defined above in (a) and (1. alkyl, aryl and cycloalkyl carboxylic groups wherein the hydrocarbon part is defined as above in (a) and (b);

e. aryl groups of 6 to 24 carbon atoms such as phenyl, naphthyl, anthryl, and the like;

f. aryl substituted alkyl wherein the aryl is phenyl which may contain lower alkyl and/or hydroxy substituents so that the resulting hydroxy aromatic is, for example, a bisphenol; and

g. mixtures of the aforesaid hydroxy aromatics.

Suitable substituted phenols include the following: para-phenyl phenol, para-benzyl phenol, para-betanaphthy; phenol, cetyl phenol, para-cumyl-phenol, para-tart-butyl phenol, sec-butyl phenol, para-tartamyl phenol, para-tert-hexyl phenol, para-alphanaphthyl phenol, para-hydroxyacetophenone, parahydroxybenzophenone, para-isooctyl phenol, para-tertoctyl phenol, para-cyclohexyl phenol, para-t-limonen phenol, para-l-limonene phenol, a phenol alkylated with oleic acid, such as phenol alkylated with oleic acid, para-decyl phenol, para-dodecyl phenol. paratert-decyl phenol, butyl naphthol, amyl enthranol, para-nonyl phenol. para-methyl phenol, bisphenols such as para, para-isopropylidene diphenol, para, para'-methylene diphenol, as well as the corresponding ortho-derivatives of the previously mentioned compounds such as ortho-butyl phenol and ortho-nonyl phenol as well as mixtures thereof, and aniline.

Mixtures of various hydroxy aromatic compounds mentioned herein also may be used.

Included among the phenolic reactants which may be used are those known as the cresylic acids and these often comprise a heterogeneous mixture of having the reacting hydrogen positions on each of them; that is, compounds unsubstituted in the orthoand parapositions of the molecule, to compounds that only have one functional position, and hence, relatively unreactive. These compounds may include the following: 3,5- xylenol, m-cresol, 3,4-xylenol, 2,5-xylenol, 2,3-xylenol, phenol, p-cresol, ortho-cresol, 2,4-xylenol, and 2,6- xylenol. Cresylic acids or tar acids are generally applied to phenol and its homologs which may include cresols, xylenols, trimethyl phenols, ethyl phenols, and higher boiling materials such as dihydroxy phenols, polycyclic phenols and the like. They are often obtained by a lowtemperature trimerization of coal, lignite, and the like, or a conventional high-temperature coke oven tar, or the liquid product of petroleum cracking both thermo and catalytic, shell oil, coal hydric hydrogenation products, and the like.

Polyhydroxy aromatic reactants, such as resorcinol, may also be used.

Particularly useful in this invention are mixtures of aniline and phenol to react with an aldehyde or ketone to produce either a novolac or a resole, depending on the other conditions described above.

Also useful in the invention are mixtures of urea and phenol to react with the aldehyde or ketone to produce either a novolac or a resole depending on the other conditions described above.

Among the aldehydes which may be used within the scope of this invention to produce either the resole or the novolac, are formaldehyde or any of its variations, such as 37 percent formalin concentration or paraldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, isopentaldehyde, and the like. The aldehyde should have not more than 8 carbon atoms and should not detrimentally affect the resinification or oxyalkylation of the resin. Preferred aldehydes are those having from 1 to 4 carbon atoms, such as formaldehyde, which may be in aqueous solution (37 percent), or in any of its low polymeric forms such as paraform or trioxane. Other aldehydes include para-aldehydes, furfural, Z- ethyl-hexanol, ethylbutyraldehyde, heptaldyde and glyoxal, benzaldehyde and crotonaldehyde.

Novolacs To prepare a novolac, the proportion of aldehyde to v be condensed with the hydroxy aromatic compound may be varied in order to obtain different molecular weights, and the viscosity of the finished resin may be controlled by the mole weight of the novolac; preferably the proportion of aldehyde employed is from 0.5 to 1.0 per mole of the hydroxy aromatic compound.

Among the substituted phenols which may be used to prepare the novolacs for this invention are those substituted with long-chain ethylenically unsaturated hydrocarbons, such as the linseed-type oils. However, it is within the scope of this invention to employ any animal and/or vegetable oil which achieves the objects of this invention based on the similarity in properties with the long-chain hydrocarbon oils. Such oils would be positioned on the phenol in the orthoor parapositions, and preferably in the paraposition. Many of them are similar in properties to linseed oil having nonconjugated unsaturation of at least 50 iodine number, and have sufficient compatibility with the novolac after it is polymerized. Safflower oil is typical of these oils. It may be in the form of a glycerol ester of the fatty acids wherein the fatty acids are of a composition comprising more than 40 percent by weight of linoienic acid. The remaining percentages of fatty acid can be any saturated or ethylenically unsaturated fatty having 12 to 22 carbon atoms and more preferably oleic and linolenic acid so that the fatty esters have an iodine number of at least 50. The iodine value (iodine number) is a measure of unsaturation, and is defined as the number of grams of iodine required per 100 grams of unsaturated material to obtain the saturated material. In addition to thepreferred glycerol ester, other polyhydric alcohols can be reacted with the described fatty acids to produce a low acid number ester of a polyol having 2 or more hydroxyl groups. Typical polyols include ethylene glycol, diethylene glycol, pentaerythritol, dipentaerythritol, sorbitol and the other polyhydric alcohols.

The acid catalyst to be used when preparing the novalacs to be used in this invention may be chosen from oxalic acid, sulfuric acid, hydrochloric acid and other strong acids used in the art for preparing novolacs. In addition, wetting agents of the anionic type, such as sodium alkylaryl sulfonates, are also useful as secondary catalysts in preparing novolacs.

The two-stage resins are curable by reaction with hexamethylene tetramine to form dibenzyl and tribenzyl amines, as well as hexatriphenol. One may also use ammonium hydroxide, which reacts with the formaldehyde to form hexamethylene tetramine. Other amines may also be used, such as ethylene diamine or ethylene triamine, or methylamines, etc. These can be used to react with formaldehydes to form a composition similar to hexamethylene tetramine. The resulting compound would be an aldehyde donor.

The phenol aldehyde novolac type resin is prepared by charging the desired phenol and aldehyde raw materials and catalysts to a reaction vessel. The reaction begins at about 100 degrees C. and proceeds under temperatures up to about 200 degrees C., at any pressure up to about 100 lbs/square inch guage for about 1 /2 hours, or until the desired degree of polymerization has taken place. Thereafter, the catalyst is neutralized where necessary, and the excess reactant, water, and other materials are taken off by dehydration and the molten resin is discharged from the vessel. It has been found that a novolac which has not been neutralized and is stable will cure more rapidly with a resole than a novolac which has been neutralized From the foregoing, it is apparent that many hydroxy aromatic compounds may be used in practicing the present invention to provide a novolac which can be then reacted with an hydroxy aromatic aldehyde resols to form the friction particle of this invention, provided the aromatic hydroxyl group is reactive and the-hydroxy aromatic compound is capable of reacting with an aldehyde or a mixture of aldehydes to produce a novolac condensete. Pure, refined phenols may be used, but this is not necessary. For instance, phenols may be alkylated and then may be reacted in crude form with an aldehyde. In such crude form, the phenols may contain some polyalkylated, as well as non-alkylated, phenols.

The process for alkylation of a phenol is well-known in the art. First, dehydration (of water) is carried out with vacuum at elevated temperatures, for instance, between about 100 and about 150 degrees C. under a vacuum of between about and about inches of mercury. Then, the dehydrated phenolic material is acidified to a pH of between about 1 and about 5 with H SO or in some cases BF Following this, a terpens or vegetable oil is added and the reaction mixture heated to between about 80 and about 140 degrees C. at atmospheric pressure. The molar ratio of reactants is between about 0.l mole of terpene or vegetable oil per mole of phenol to about 2.5 mole of terpene or vegetable oil per mole of phenol. When tung oil is employed as a vegetable oil in the alkylation, use of BF to acidify would cause gelation, so it is not used, but H 50, can be used.

The proportion of aldehyde to be condensed with the hydroxy aromatic compound to form a precondensate may be varied to prepare novolacs of different molecular weights. Viscosity of the finished precondensate may be controlled by the mole weight of the novolac. Preferably, the proportion of aldehyde employed varies from about 0.5 to 1.0 mole per mole of phenol when a monoor difunctional phenol is used. In instances where a trifunctional phenol is used, i.e., unsubstituted .in the orthoand parapositions, a preferred upper limit of the aldehyde may be about 0.70 mole of aldehyde per mole of phenol so as to minimize the formation of insoluble, infusible condensates. It is preferred that the aldehyde and phenol be condensed using an acid catalyst to shorten the time required for complete condensation of the reactants. Suitable acid catalysts include sulfuric acid, hydrochloric acid, and oxalic acid. These catalysts are generally employed in the amount of 0.1 to about 5 percent by weight of phenol to be condensed.

Where a mixed aldehyde, phenolaldehyde precondensate is to be prepared, it is formulated by charging the desired phenol and aldehyde raw materials and catalysts to a reaction vessel. The reaction proceeds under temperatures from about 25 to about 150 degrees C. at a pressure from about ambient up to about 100 pounds per square inch gauge pressure for a period of time from about 5 minutes to about 5 hours, a suitable time being about 1% hours, or until the desired degree of condensation has taken place. The phenol is first reacted with the longer-chain aldehyde to form a phenol longer chain aldehyde precondensate, followed by a second-step reaction of the phenol-longer chain aldehyde precondensate with formaldehyde to form a thermosettable phenol aldehyde precondensate material. In the second step, the reactants are refluxed at atmospheric pressure, although higher reflux temperatures up to about 150 degrees C. can be used by employing elevated pressure. The formaldehyde can be added all at once in the second step, or added gradually. If the formaldehyde is added all at once, then a temperature range between about 50 and about 60 degrees C. is used at the beginning of the second-step reaction, until the exothermic reaction subsides, and then the temperature is increased slowly to between about and about degrees C. and held until further exothermic reaction subsides, and then the reaction mixture is heated to reflux temperature which is about degrees C. at atmospheric pressure. If elevated pressure is used, then the reflux temperature can be increased to as high as about degrees C. If the formaldehyde is added gradually in the second step, then a temperature range between about 95 and about 140 degress C. can be used. The catalyst is then neutralized and the excess reactant, water and other materials are taken off.

While the precondensate is still at an elevated temperature, from about 25 degrees to about 150 degress C., but below the boiling point of the resultant solution or supension, with about 100 degress centigrade being very suitable,it may be reduced in viscosity by addition of suitable solvent. The amount of solvent may vary from about 10 to 70 percent of the precondensate by weight and a suitable ratio of precondensate to solvent is about 10 parts of precondensate to 9 parts of solvent. The controlling factor is the resulting viscosity of the precondensate prepared, rather than the actual volume of solvent charged. Among the solvent which may be used for this purpose are ethanol, methanol, toluene, xylene, ketones, such as acetone, and methylethyl ketone, and mixtures of aromatic and aliphatic hydrocarbons, such as mixtures of benzene and mineral spirits, or benzene and acetone.

Oxyalkylation Oxyalkylated resins are prepared which preferably contain substantially no free reactive hydroxy aromatic groups for example, less than about 0.5 percent of the aromatic hydroxyl present originally in the hydroxy aromatic or hydroxy aromatic aldehyde condensate. To remove the aromatic hydroxys, the hydroxy aromatic aldehyde resin can be reacted with a compound which etherifies the aromatic hydroxyl groups so that almost all of the aromatic hydroxy groups present in each hydroxy aromatic aldehyde condensate unit are so reacted.

The preferred method of hydroxyalkylation is by reaction with compounds containing a mono-oxirane ring. Such compounds include ethylene oxide, propylene oxide, butylene oxide, styrene oxide and cyclohexene oxide, glycidol and epichlorohydrin. Many other monoepoxides can be used, but the alkylene oxides containing not more than 6 carbons are generally preferred. Additional useful compounds are phenyl glycidyl ether and related compounds prepared from the reaction of epichlorohydrin and monofunctional alkylated and halogenated phenols such as pentachlorophenyl glycidyl ether.

Catalysts for the reaction of the oxirane ring compounds and phenollc hydroxyl groups may be alkali or alkaline earth hydroxides, primary amines, secondary amines, tertiary amines or basic alkali salts. These include sodium, potassium, lithium, calcium and barium hydroxides, amines such as methyl, dimethyl, diethyl, trimethyl, triethyl, tripropyl, dimethyl benzyl, dimethyl hydroxyethyl, dimethyl-Z-hydroxypropyl and the like, and salts of strong bases and weak acids such as sodium acetate and benzoate.

The reaction may becarried out at temperatures of about'room temperature to 250 degrees C., and preferably in the absence of solvents, although solvents may be used to reduce viscosity when desired. When oxyalkylating resoles, the reaction should be carried out .at lower temperatures than when oxyalkylating novolacs, because there is a possibility that reaction of the methylol groups with other methylol groups gives methylene linkages, formaldehyde and gelation. When oxyalkylating a novolac, temperatures between room temperature and about 200 degrees C. can be used. When'oxyalkylating a resole, temperatures between room temperature and about 100 degrees C may be used.

The aromatic hydroxyl of the novolacs may also be hydroxyalkylated by reacting alkylene halohydrins with the aromatic hydroxyl using equivalent amounts of an alkali metal hydroxide to bring about the reaction. Suitable alkylene halohydrins are ethylene chloroand bromohydrins, propylene chloroand bromohydrins, 2,3- butylene chloroand bromohydrins, and glyceryl chloroand bromohydrins.

Another method for hydroxyalkylating novolacs is reaction with alkylene carbonates such as ethylene carbonate and propylene carbonate, using a catalyst such as potassium carbonate.

At least one mole of alkylene oxide or other etherifying or esterifying agent is required per mole ofaromatic hydroxyl. However, resins prepared by reaction with up to 7 moles of alkylene oxides per mole of phenolic hydroxyl have been found to be useful.

Resoles The liquid one-stage resin (resole) which forms a part of this invention may be formed by reacting an hydroxy aromatic compound with an excess of formaldehyde in alkali such as sodium hydroxide dissolved in water. The reaction mixture is gradually heated to reflux and held at reflux until less than about 1 percent of free formaldehyde remains. This provides a preferred reaction product which has less than 2 percent of the formaldehyde unreacted, although this is not critical in this process. Less than 2 percent free CH O is desirable. The reaction mixture is then cooled and the catalyst neutralized with some acid such as glacial acetic acid and the pH is adjusted to roughly 6 to 7.5. The reaction mixture may be then further reacted with hexamethylene tetramine or some other aldehyde donor, i.e., curing agent. The resin is then dehydrated to between about 50 to 95 percent solids, and preferably between about 81 to 85 percent solids.

The alkaline catalyst used in preparing the resoles to be used in this invention may be any of those known in the art; for instance, sodium hydroxide and calcium hydroxide. In general the alkali metal hydroxides and the alkaline earth metal hydroxides and ammonium hydroxide and the amines such as triethanol amines may be used.

Following the intercondensation reaction to form a resole, a stoichiometric quantity of a strong acid such as sulfuric acid, hydrochloric acid, phosphoric acid or oxalic acid, or the like, is added to the reaction mixture in order to neturalize the alkaline condensation catalyst. Sulfuric acid is conveniently employed to neutralize a sodium hydroxide catalyst. The alkaline catalyst may also be neutralized by dilution through repeated washing, however, it is preferred to use an acid. The final resin should have a pH between about 5.5 and 7.5 for good stability.

The hydroxy aromatic compound employed in a resole can be alkylated, if desired, with alkyl groups containing l to 12 carbon atoms, or with unsaturated groups, including the long-chain unsaturated vegetable or animal oils, to form alkylated hydroxy aromatic compounds that when reacted with an aldehyde from heat reactive resoles. These include alkylene groups of 2 to 36 carbon atoms, fatty acids, polyethers, alkyl ethers, polyesters and polyols and mixtures of these.

Among the high molecular weight or polymeric materials containing aliphatic carbon-to-carbon unsaturation, there are included such naturally occurring materials as unsaturated vegetable, fish or animal oils such as linseed, soya, tung, sesame, sunflower, cotton seed, herring, menhaden, and sardine oils, etc., or chemically modified naturally occurring materials such as ally] ethers of starch, cellulose or acrylate esters thereof, etc., synthetic drying oils, polymers obtained by polyetherification of such unsaturated compounds such as maleic, fumaric, itaconic, aconitic, chloromaleic, dimerized fatty acids, anhydrides or acids from allyl glycerol, methallyl glycerol ether, glycerol monoacrylate, butene diol, pentene diol, or polymers obtained by polyetherification of the unsaturated polyols. Other oils include castor oil, tall oil, oiticica oil, safflower oil, and the .like, oleic and linolenic acids. These fatty acids have from 12 to 22 carbon atoms. They are often in combination as a glycerol ester or in combination with other polyhydric alcohols or polyols such as ethylene glycol, diethylene glycol, pentaerythritol, dipentaerythritol, sorbitol, and the like polyhydric alcohols.

The blending and reacting of the resole with the other components in accordance with this invention may be in various proportions, depending upon the ultimate properties desired in the friction particle to be produced, but will generally be in the range of about 60 to about 95 weight percent of the non-oxyalkylated resole based on the total weight of resin components.

It is to be understood that the oxyalkylated resole or oxyalkylated novolac described herein will not be a friction particle alone unless reacted with a nonoxyalkylated, non-alkylate resole resin or with a nonoxyalkylated, alkylated resole resin. The oxyalkylated resole product is a liquid and will not cure. The preferred compositions of the invention contain at least one of an oxyalkylated resole and an oxyalkylated novolac in combination with the non-oxyalkylated resole.

The friction particle of this invention may be used alone or with other friction materials known in the art. A typical friction element contains about 30 to 60 weight percent asbestos fiber, up to 40 weight percent other inorganic filler and abrasives, about to 15 weight percent organic filler, including the particle of this invention, and about 15 to 30 weight percent binder; all percents are by weight of total composition. Asbestos fiber, other abrasive materials and filler materials are charged into a mixer followed by the addition of a binder, such as a varnish material. The materials are kneaded until the fiber, abrasives, and any fillers are thoroughly wetted and a uniform mass is obtained. The mass is discharged from the mixer, rolled out into sheets or extruded or pressure molded and dried, after which it is ready for further processing into friction elements.

The abrasives, that is, the friction imparting agents and fillers, which may be used in addition to the abrasive material disclosed and claimed herein, within the scope of this invention include, but are not limited to brass chips, metal shavings and fillings, silica, talc, wood flour, chalk, clay, mica, fiber glass, felt, carbon black, graphite, metal nitrides and oxides, and ground cashew nut shell oil polymerizate. These abrasives and fillers may be used in addition to the friction particle of this invention to achieve the particular amount of bulk and coefficient of friction desired. Some consumer specifications specify that the friction particle should be 90 percent finer than mesh and coarser than 100 mesh. Other consumer specifications call for coarser or finer friction particles.

EXAMPLE 1 PART A (The Resole) A reaction vessel is charged with parts of phenol, 5 parts of cresylic acid, parts of formalin (37 percent formaldehyde) and 1.0 part of flake caustic dissolved in 4 parts of water. This reaction mixture is heated gradually to reflux and held at reflux to less than 5 percent free formaldehyde and cooled to 70 degrees C., after which 1.5 parts of glacial acetic acid is added which neutralizes this composition to a pH of 6.8-7.2. After the pH range is achieved the resin is dehydrated to 8l-85 percent solids and cooled to room temperature. The resultant product is a viscous liquid, and is identified as re in Ra in Table V.

PART B (The Oxyalkylated Novolac) The oxyalkylated novolac may also be referred to as a polyol of a novolac which is oxyethylated, using from about .one mole to about 7 moles of ethylene oxide to 1 mole of phenol, depending on the properties desired. For this Example, a resin was used with a ratio of 2 moles of ethylene oxide to one mole of phenol.

A typical modified phenol-aldehyde condensation product is prepared by introducing 3,000 parts phenol, 13 parts of oxalic acid catalyst and 6 parts of a wetting agent of Nacconol (sodium alkylaryl sulfonate) into a jacketed reactor and heating to 100 degrees C. (The anionic wetting agents of alkylaryl sulfonate type are preferred.) Then 1,110 parts of a 37 percent aqueous formaldehyde solution are added to the reactor at a rate that the heat of reaction provides a vigorous reflux. Refluxing is continued for 2 hours after the completion of the formalin addition. The reactor contents are dehydrated at degrees C. and then dephenolated at 200 degrees C. at 50 millimeters vacuum. Approximately 2,030 parts of phenol-aldehyde condensate are produced. Then 7.2 parts of sodium hydroxide are introduced to the reactor. Ethylene oxide is then added to the reactor as either a vapor or a liquid, The reactor temperature is maintained at degrees C. for the initial 2 hours and is then permitted to increase to the range of 200 to 220 degrees C. until the addition of 878 parts of ethylene oxide is complete. The resulting condensation product had a hydroxyl number of 370, and a Gardner viscosity at 50 degrees C. of about 2,000 seconds, and is resin NF in Table VI.

The novel friction particle is made by blending 60 parts of Part A with 40 parts of Part B, curing 8-16 hours at 325 to 375 degrees F., grinding to the desired screen size necessary for a friction particle useful in the arts. In this particular Example, the blend was cured for 16 hours at 350 degrees F. and ground to 20 mesh. The resulting particle was made up into a brake lining, tested by standard procedures and found to be satisfactory for this use.

EXAMPLE 2 70 parts of Part A and 30 parts of Part B of Example 1 were blended and reacted, using the same curing cycle as in Example 1. The resulting product was ground to 20 mesh and found to be superior to a polymerized cashew nut shell oil friction particle known as Cardolite in the trade, having softening properties at 500 degrees Fahrenheit when compressed slightly with an 8 inch spatula /s wide by 4 long X 1/32 inch thick blade). Also the heat loss at 700 degrees F. was lower than that of Cardolite.

To an internal mixer equipped'with a Sigma-type blade were charged the Dry Mix and hexamethylenetetramine. The dry materials were mixed an blended for 5 minutes. Then the varnish and toluene were EXAMPLE 3 5 added and mixed for 1 hour until the mass was uniform. The dough ltke mix was then discharged from the 80 Parts of Part A and 20 Parts 9 Part B of Example mixer and charged to an extruder. The extruder is 1 Wereblended and reacted, 115mg 1 Same Cufmg equipped with a 2 by A inch rectangular die and has an Cycle as Example The l g Product was applied ram pressure of 100 to 300 pounds per square ground to 20 m and had P p slmllar to those inch. The dough-like mix was then extruded in a shape of the p f of f p which was satisfactory for brake linings. The extruded The particles obtained in the above Examples 1, 2 linings were oven dried for 3 hours and with a gradual and 3 were superior to friction particles made from poinc s of temperature up to about 88 degrees C. to lymerrzed cashew nut shellotl commonly called Carremove solvents and other volatiles. The linings were d01rte, presently used as friction particles in the brakeh t t proper l n th, h ated for 2 to 3 minutes lining industry. The particles made in accordance with t bo t 163 degrees C,, bent or arched to the desired the invention are less SUbjBCt to migration of compocurvature and placed into forms (i.e., molds) for curnents which results in brake linings with better fade" ing. These linings were then cured for 8 hours at about characteristics. The particles of the invention are more 205 degrees C. The cured linings after cooling were exheat resistant and can be made with more uniform panded to the proper size for mounting into brake quality, with better control of end properties. The parshoes. The resulting friction elements were found to be tlcles are less toxic to the skin than Cardolite, which satisfactory for use on automobile brakes. has the further disadvantage of being solely available from foreign sources. The products of the invention EXAMPLES-l2 can also be made at lower cost. In Table 1, Examples 5-12 are shown in tabular form. In each of these Examples, (except Examples 10, 11 and 12) the resins were weighed into a beaker and me- EXAMPLE 4 chanically mixed. The mix was spread into aluminum pans (2% by 7 inches) and cured in an air-circulating The friction particle (7 parts) of Example 1 was used oven at the specified temperature and time. The form umformulatmg a mixture comprising 62.37 parts of Dry lations for the resoles and novolacs used are given in MIX, 0.63 part of hexamethylenetetramine, 16.4 parts Tables V and V1, respectively. Example 10 is a repeat of varnrsh, 20 parts of rubber solvent (mainly mineral of Example 2. In Example a Cardolite, splrlt) and 0.6 part water. The Dry Mix is composed of 420 sample of cashew nut shell oil friction particles is 93 parts by weight of asbestos shorts, Quebec Standard given for comparison purposes. In Example 1 SinCe AsbestosGrade 7K, and 7 parts by weight of the fricboth resins are liquids, the materials were mixed in a 15 tron particles. The moisture content of the Dry Mix is gallon kettle. In all other respects, however, the proceheld low between 0.75 and 1.0 percent to avoid any dures and equipment were the same as the other Exampossrbrlrty of blistering of the element dgringcure. ple in Table 1- TABLE 1 Example Height Cure Cure Volatile Acetone Hot Plate Behavior at Number Resale Novolac Ratio Temp. Time Loss Extract 5()(1F Spatula Test able Resin Resin Resole/ Wt. Formula Wt. Formula Novolac "C Hrs. 71

5 195 Re 15 Na 90/10 175 16 11.93 2.07 Smoky, softens slightly under spatula pressure 6* 195 Rc 15 Na 90/10 175 16 14.3 3.14 Smoky. softens slightly under spatula pressure 7 225 Rf 15 Na 90/10 175 16 22.7 13.66 Very smoky. softens slightly.

. color change 8 162 Re Nd /30 175 16 13.6 26.61 Smoky. changes to a wet, oily ness soft 9 225 Rf 15 Nd /10 r75 16 17.9 11.52 Smoky, softens slightly 10 140 Ra 60 Nf 70/30 16 24.9 21.65 Smoky, very slight softening.

color change 11 Cardolite NC-104-20 Cashews Nut Shell 011 Friction Particles 25.9 2.59 Very smoky, softens slightly.

oily odor. particle breakdown 12 Rg 60 Nf 70/30 120 22 17.27 3.63 Smoky, slight softening. color change 2.4 grams of hexamethylcne tetraminc were also added into the mix Weights are in grams Volatile loss is at 70t1F for one hour Acetone exrructahlc test is ASTM D-494-46 All materials tested were ground through 211 mesh Ratio is of resln snlitl content The results presented in Table 1 indicate that the commercial Cardolite friction particle has a high volatile loss when heated at 700F. for 1 hour, a low acetone extractable content and deteriorated when heated to 500F. ona hot plate. By contrast, the products of 5 the invention were more stable at elevated temperatures. The results also exhibit the control over properties that is possible with compositions of the invention. Thus, a low acetone extractable content indicates a hard material, a high acetone extractable content indicates a softer material.

EXAMPLES 28-46 TABLE I11 VARlATlONS ON EXAMPLES 12 AND 14 IN TABLE 1 Example Resole Novolac Cure Time Cure Temp. Volatile Acetone Number Formu- Formu- Ratio Hours C Loss, Extractable,% Comments lation lation 28 Ra- Nf 70/30 1 200 9.4 23.58 Mixed under vacuum while heating from 85C to 125C. Hot plate cure 59 sec.

79 Ra Nf 70/30 16 120 21.4 28.59 Mixed under vacuum while heating from 85C to 105C.

' Hot plate cure 72/77 sec. 30 Ra Nf 60/40 16 120 16.96 41.8 Mixed under vacuum while heating from 85C to 90C. Hot plate cure 101/106 sec 31 Ra Nf 70/30 16 120 14.0 24.5 Mixed under vacuum while heating from 85C to 105C.

Hot plate cure 46/51 sec. 32 -Ra Nf 70/30 2 200 14.2 32.63 Resins physically mixed 33 Ra Nf 70/30 5 180 19.7-21 8 17.5-22.4 Hot plate cure 55/60 sec. 34 Ra Nf 70/30 4 180 12.5-15 0 22.2-23.8 35 Ra Nf 70/30 0.1 440 23.5-25 1 8.65-12.33 Resins physically mixed 36* Ra Nf 70/30 0.05 440 27.4 15.67 Resins physically mixed 37 Ra Nf 70/30 5 min. 600F 23.6 19.45 Resins physically mixed 38 Ra Nf 70/30 6 min. 600F 24.8 17.76 Resins physically mixed 3) Ra Nf 70/30 7 min. 600F 25.1 17.47 Resins physically mixed 40 Ra Nf 70/30 8 min. 600F 24.4 15.62 Resins physically mixed 41 Ra Nf 70/30 10 min. 600F 24.0 15.09 Resins physically mixed 42 kg Nf 70/30 3 min. 600F 22.5 5.45 Resins physically mixed 43 Rg Nf 70/30 2 min. 600F 23.3 10.34 Resins physically mixed 44 Rg Nf 70/30 4 min. 600F 22.0 7.61 Resins physically mixed 4S Rg Nf 70/30 5 min. 600F 21.6 7.02 Resins physically mixed 46, Rg Nf 70/30 8 min. 600F 21,9 4.81 Resins physically mixed Experiments 28-35 were tested for volatile loss at 600F for 2 hours and acetone extractable for 16 hours (ASTM B49446) Experiments 36-46 were tested for volatile loss at 700F for 1 hour and acetone extractable for 4 hours (ASTM D-494-46l EXAMPLES 15-27 In Table 11, Examples 15-27 are shown in tabular form. The procedure used is set forth in the footnote of Table 11. T-he formulations for the resoles and novolacs used are given in Tables V and V1, respectively.

TABLE II EXAMPLES 47-62 Example. Resolev Novolac Ratio Volatile Acetone Hot Plate Behavior at Number Formulation Formulation Resale/Novolac Loss, 7c. Extractable.% 500F Spatula Test 15 Rg 7.51 0.0 No smoking or softening l6 Ra 6.29 0.0 No smoking or softening 17 Re Nf /30 36.72 2.29 Slight softening-slight smoking 18 Re & Rd Nf 70/30 25.92 3.70 Slight softening-no smoking 19 Rg Ng 70/30 8.17 0.03 No smoking of softening 20 Ra Ng 70/30 10.23 1.68 Slight softening 21 Rg Nh /20 7.23 0.0 Slight softening 22 Ra Nh 80/20 7.00 0.18 Slight softening 23 Rg Ne 70/30 6.60 0.67 Slight smoking. no softening 24 Re Hycar 1561 /10 9.35 0.49 Very smoky. melts and turns Rubbery Latex 25 Rb & Rc Nf 70/30 18.35 0.58 No smoking, no softening 26 Rg Nc 80/20 7.0 4.34 Slight smoking. slight softening 27 Ra NC 70/30 6.45 0.60 Slight smoking. no softening All components were weighed into a beaker [2110 grams total mix) and mechanically mixed. The mix was spread into aluminum puns (2%" x 7") and cured in an air t-m'olotion own at |7' (on in hours \t\lo|\r t\\1il\illli(11k\il ASIM 1] 4 14-10 Volatile loss is at 700T for one hour All materials tested were ground through 21) mesh TABLE IV Oxyalkylated Example Resole Novolac Resin Percent Percent Hot Plate Behavior Number Formulation Formula- Formulation Ratio Volatile Loss Acetone Extractable At 500F tion 47 kg Rj 70/30 21.19 15.83 Slight smoke-very slight softening 4B Rf Rj 70/30 31.71 0.11 Smoky-softens-odor oily appearance slight caking 49 Rg & Rf Rj /35/30 26.28 31.47 Smokys|ight softening odor 50 Rg & Rh Rj 35/35/30 22.77 24.05 Slight smoke-slight softening slight odor 51 Rg Rd Rj 15/15/70 14.43 15.24 Smokysoftens0doroily-cakes 52 kg Rb Rj 70/15/15 11.57 0.89 Very slight smoke very slight softening 53 Rg & Rf /40 10.51 0.97 No smokev e y slight sofienmg 54 Rf Rf 80/20 20.13 32.99 Smoky-slight softeningodor-oily 55 Rg & Rf Rf 40/40/20 16.51 6.59 Slight smoke-slight softening 56 Rg & Rh Rj 35/35/30 17.88 13.50 Slight smoke-very slight softening 57 Rg Rg Rf /10/20 13.67 7.30 Slight smokesoftens-very oily-cakes 53 Kg Rb Rf 70/10/20 12.26 0.32 No smoke-slight softening 59 Rf& Ri 60/40 10.52 15.96 Slight smoke-softensslightly oily-slight caking 60 Rf Rf /20 12.56 18.58 Slight smokeslight s0 tentng-s 1g 1 y or y 61 Rf & Rg Rf 20/70/10 9.18 7.01 Smokysoftensoi1y- 62 Qardolite RC-104-20 Cashew Nut Shell Oil Friction Particles slight caking Smokyvery slight ef sniaw Odor TABLE v Resole Resin Formulations Resin Raw Material Acetic Acid Alcohol Ammoniacal Liquor Aniline Casein Caustic Soda Citric Acid Deodorant Formaldehyde (37.2%) Hexamethylene retrasine Lime Melamine (Buffered) Meta-Para Cresol Methanol Ortho Cresol Oxalic Acid Para-Tertiary Butyl Phenol Para-Tertiary Octyl Phenol Phenol Phosphoric Acid Propylene Oxide Sulfuric Acid Triethylamine Urea (Shotted) Urea Formaldehyde Water Xylene 1n Result: Rj. the phenol. formaldehyde and 2.5 arts ul'triethanolumine wcrc first reacted. This product is then oxypropylatcd with the remaining specified ingretlicnh.

Resin Raw M aterlal a b Ammoniacal Liquor Aniline Beta Haphthol Butyl Acid Phosphat Castor Oil Caustic Soda Ethylene Oxide Formaldehyde (37.2%) Furfural lsobutyraldehyde Lime We claim: I

11. A friction particle comprising the non-catalyzed reaction product of the reaction at about 225 to about 400 degrees F. of a nonhydroxyalkylated, nonalkylated hydroxy aromatic hydrocarbon-aldehyde resole containing substantially no etherified aromatic hydroxyl groups with a mixture of a hydroxyalkylated hydroxy aromatic hydrocarbon-aldehyde novolac with at least one member of the group consisting of a hydroxyalkylated hydroxy aromatic hydrocarbon-aldehyde resole and an alkylated hydroxy aromatic hydrocarbon aldehyde resole until the resulting product is substantially insoluble in acetone, infusible, and does not soften slightly under mechanical force at a temperature below 400 degrees F. and has substantially no cohesive or bonding strength, wherein said nonhydroxyalkylated resole comprises about 60 to about 95 percent of the weight of the resin components; wherein the hydroxyalkylated resole contains less than about 0.5 percent of the aromatic hydroxyl originally present in the hydroxy aromatic hydrocarbon aldehyde condensate; and wherein the alkylated groups are substituted on the aromatic ring and are selected from the group consisting of:

(a) alkyl groups of 1 to 60 carbon atoms,

(b) cycloalkyl groups of 5 to 12 carbon atoms,

(c) alkyl, aryl and cycloalkyl ketonic groups wherein the hydrocarbon portion is as defined in (a) and (d) alkyl, aryl and cycloalkyl carboxylic groups wherein the hydrocarbon portion is as defined in and (e) aryl groups of 6 to 24 carbon atoms, and

(f) aryl substituted alkyl wherein the aryl is phenyl,

lower alkyl-substituted phen'yl or hydroxy substituted phenyl.

TABLE V1 Novolac Resin Formulationsd e r I g h 2. The particle of claim 1 wherein the first said resole .in the particle is the condensation product of phenol and formaldehyde in an alkaline medium.

3. The particle of claim 1 wherein the said hydroxyalkylated resole in the particle is the hydrooxyalkylated product ofa phenol with an aldehyde in alkaline medium.

4. The particle of claim 1 wherein the said novolac in the particle is the condensation product of phenol and formaldehyde in an acid medium.

5. The friction particle of claim 1 which comprises from about 5 to about 40 percent by weight of a mixture of a hydroxyalkylated hydroxy aromatic hydrocarbon-aldehyde novolac and an alkylated hydroxy aromatic hydrocarbon resole.

6. A brake lining comprising the cured product of a friction particle of claim 1, a resin binder and an inorganic filler.

7. A brake lining comprising the cured product of about 30 to 60 weight percent of asbestos fiber, up to 40 weight percent of other inorganic fillers and abrasives, about 5 to 15 weight percent of a friction particle of claim 1 and about 15 to 30 weight percent of a binder.

8. A brake. lining comprising the cured product of about 30 to 60 weight percent of asbestos fiber, up to about 40 weight percent of other fillers and abrasives, about 5 to 15 weight percent of a friction particle of claim 5, and about 15 to 30 weight percent of binder.

9. The friction particle of claim 1 which comprises the reaction product of about 5 to about 40 percent by weight of a hydroxyalkylated novolac and about to about 60 percent by weight of a mixture of an alkylated & e. 

1. A FRICTION PARTICLE COMPRISING THE NON-CATALYZED REACTION PRODUCT OF THE REACTION AT ABOUT 225 TO ABOUT 400 DEGREES F, OF A NONHYDROXYALKYLATED, NON-ALKYLATED HYDROXY AROMATIC HYDROCARBON-ALDEHYDE RESOLE CONTAINING SUBSTANTIALLY NO ETHERIFIED AROMATIC HYDROXYL GROUPS WITH A MIXTURE OF A HYDROXYALKYLATED HYDROXY AROMATIC HYDROCARBON-ALDEHYDE NOVOLAC WITH AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF A HYDROXYALKYLATED HYDROXY AROMATIC HYDROCARBON-ALDEHYDE RESOLE AND AN ALKYLATED HYDROXY AROMATIC HYDROCARBON ALDEHYDE RESOLE UNTIL THE RESULTING PRODUCT IS SUBSTANTIALLY INSOLUBLE IN ACETONE, INFUSIBLE, AND DOES NOT SOFTEN SLIGHTLY UNDER MECHANICAL FORCE AT A TEMPERATURE BELOW 400 DEGREES F, AND HAS SUBSTANTIALLY NO COHESIVE OR BONDING STRENGTH, WITHIN SAID NON-HYDROXYALKYLATED RESOLE COMPRISES ABOUT 60 TO ABOUT 95 PERCENT OF THE WEIGHT OF THE RESIN COMPONENTS; WHEREIN THE HYDROXYALKTLATED RESOLE CONTAINS LESS THAN ABOUT 0.5 PERCENT OF THE AROMATIC HYDROXYL ORIGINALLY PRESENT IN THE HYDROXY AROMATIC HYDROCARBON ALDEHYDE CONDENSATE; AND WHEREIN THE ALKYLATED GROUPS ARE SUBSTITUTED ON THE AROMATIC RING AND ARE SELECTED FROM THE GROUP CONSISTING OF: 8A) ALKYL GROUPS OF 1 TO 60 CARBON ATOMS, (B) CYCLOALKYL GROUPS OF 5 TO 12 CARBON ATOMS, (C) ALKYL, ARYL AND CYCLOALKYL DETONIC GROUPS WHEREIN THE HYDROCARBON PORTION IS AS DEFINED IN (A) AND (B) (D) ALKYL, ARYL AND CYCLOALKYL CARBOXYLIC GROUPS WHEREIN THE HYDROCARBON PORTION IS DEFINED IN (A) AND (B), (E) ARYL GROUPS OF 6 TO 24 CARBON ATOMS, AND (F) ARYL SUBSTITUTED ALKYL WHEREIN THE ARYL IS PHENYL, LOWER ALKYL-SUBSTITUTED PHENYL OR HYDROXY SUBSTITUTED PHENYL.
 2. The particle of claim 1 wherein the first said resole in the particle is the condensation product of phenol and formaldehyde in an alkaline medium.
 3. The particle of claim 1 wherein the said hydroxyalkylated resole in the particle is the hydrooxyalkylated product of a phenol with an aldehyde in alkaline medium.
 4. The particle of claim 1 wherein the said novolac in the particle is the condensation product of phenol and formaldehyde in an acid medium.
 5. The friction particle of claim 1 which comprises from about 5 to about 40 percent by weight of a mixture of a hydroxyalkylated hydroxy aromatic hydrocarbon-aldehyde novolac and an alkylated hydroxy aromatic hydrocarbon resole.
 6. A brake lining comprising the cured product of a friction particle of claim 1, a resin binder and an inorganic filler.
 7. A brake lining comprising the cured product of about 30 to 60 weight percent of asbestos fiber, up to 40 weight percent of other inorganic fillers and abrasives, about 5 to 15 weight percent of a friction particle of claim 1 and about 15 to 30 weight percent of a binder.
 8. A brake lining comprising the cured product of about 30 to 60 weight percent of asbestos fiber, up to about 40 weight percent of other fillers and abrasives, about 5 to 15 weight percent of a friction particle of claim 5, and about 15 to 30 weight percent of binder.
 9. The friction particle of claim 1 which comprises the reaction product of about 5 to about 40 percent by weight of a hydroxyalkylated novolac and about 95 to about 60 percent by weight of a mixture of an alkylated resole and a non-hydroxy-alkylated, non-alkylated resole. 